Impeller pump with noise suppressing means



March 24, 1953 J, ANDREWS IMPELLER PUMP WITH NOISE SUPPRESSING MEANSFiled Jan. 9, 1951 3nvcntor J phn M.Andrews @v s-(l Fief) rill/fill!!! 1attornegs Tatented Mar. 24, 1953 IMPELLER- PUMP WITH NOISE SUPPRESSINGMEANS John M. Andrews, York, Pa., assignor to York Corporation, York,Pa., a corporation of Delaware Application January 9, 1951, Serial No.205,159

This invention relates to centrifugal pumps, and particularly tosilencing devices therefor.

Installations are known in which a pump running more or lesscontinuously removes liquid from a sump. It sometimes happens that therates at which liquid accumulates, and the rate atwhich the pumpoperates are independent, so that the sump is occasionally pumped dry,or nearly so. Continued operation of such a pump when empty causes aloud and disagreeable chirping noise.

An example may be taken from the room cooler art. The evaporator in theroom circuit of the conditioner is operated at temperatures which fromtime to time are below the dew point of the air, so that moisturecondenses on the evaporator from the air and runs off the evaporator asdrip. This drip in certain types of coolers is drained to a sump inwhich a pump operates. Even if the machine runs constantly, the rate ofaccumulation varies with the humidity of the air. The pump in the sumppropels the drip to means which cause its re-evaporation by heat fromthe condenser, and the connections are such that the re-evaporated dripis delivered to, and discharged out of doors with, the condenser-coolingair-stream.

Silent operation of the machine is obviously important. The invention isbased on the discovery that a constantly running centrifugal pump can besilenced when the pump is empty or nearly so, by providing means whichretain by capillarity a body of water which blinds the pump inlet ports.Whether the chirping noises heretofore encountered are prevented fromoccurring or are merely mufiled (and either or both effects may bepresent) the noise can be suppressed to the point of inaudibility.

All that is required is a configuration such that the approach to thepump inlet ports is through a passage of capillary thinness betweenplates, and of such extent that the suction of the pump when empty ofwater or substantially so, is insufiicient to overcome capillaryretention of water in the approach path to the inlet ports. The resultcan readily be secured because the suction effect of a water-free pumpis small, and the area of capillary retention can be made quite largewithout seriously throttling inlet flow to the pump when the sump fillswith water. The term capillary thinness" is used in the familiar senseto indicate an interplate interval small enough to assure capillaryretention of water.

The invention will now be described in a form 4 Claims. (01. 103-103)pan II to supply water to chamber I2.

in which it has been incorporated in a room cooler, reference being madeto the accompanying drawing, in which:

Fig. 1 is a vertical section on the line I-I of Fig. 3.

Fig. 2 is a vertical section on the line 22 of Fig. 1.

Fig. 3 is a fragmentary plan view showing the configuration of th pumpchamber.

A drip collecting pan II is mounted in the bottom of the conditioner, orin any position where it will collect drip water. A portion of thebottom of the pan is pressed downward to form a circular pump chamber I2with discharge passage |3 at its periphery (see Fig. 3).

A cap plate I4 is seated on gasket I5 and held by bolts I6, so that itforms the upper wall of pump chamber I2 and passage I3. The plate Itcarries a discharge tube connection I! which leads from passage I3.

A bracket I8 fixed to plate I4 supports bearing I9 which is bolted to itat 2|. Bearing I9 supports impeller shaft 22, which extends verticallydownward through a central opening in plate 44 and carries impeller 23which in the form illustrated is a flexible strip of rubber in chamberl2. Near shaft 22 inlet ports 24 (two of which are visible in thedrawing) are formed in plate I4. The approach path to ports 24 isthrough an interval of capillary width between plate I4 and an overlyingplate 25. Plate 25 has an ofiset flange 26 which is welded to plate I4,and a spacing flange 2'! which can, but need not be welded to plate I4.

A peripheral flange 28 serves as means to attach a screen 29 whichprotects the approach path to ports 24, i. e., the path between platesi4 and 25.

Shaft 22 may be driven by any preferred means. In Fig. 1 the shaft 3| ofone of the fans 32 is connected by a flexible shaft 33 (constructed ofhelically wound wire) to the upper end of impeller shaft 22.

The impeller runs continually. The plate 25 is submerged when there iswater enough in Hence, the capillary entrance path is supplied withwater as a necessary incident to operation of the pump. When the pumphas cleared itself of water the capillary retention of water betweenplates I4 and 25 is strong enough to resist any suction developed by theimpeller. Hence, the entrance ports are blinded by water. Whatever theprecise cause may be, the effect is to.

silence the chirping noise which develops under these conditions ifplate 25 is absent.

Obviously the concept may be embodied in various specifically differentforms. It offers a simple and effective solution of a troublesomeproblem.

What is claimed is;

1. In a, liquid. pump of the impeller type, the.

combination of a rotary impeller; a housing having a chamber in whichthe impeller is mounted; to rotate, said chamber havin an inletnear its.

center and a discharge connection near its periphery; and meansafiording closely spaced surfaces defining an approach passageto said.inlet, the spacing and xtent of the definin surfaces being such as toassure capillary retention of water in said approach passage.

2. The combination defined in claim 1 in which the surfaces which definethe approach passage are substantially horizontal.

3, In a liquid pump, of; theimpeller, type, the

combination of, a rotary impeller; a housing having a chamber in whichthe, impeller is mounted tqrqtate, said; chamber having aninlet near itscenter and a discharge connection near its, periphery; means a fordingclosely spaced surfaces defining an approach passage to said inlet, thespacing and extent of the defining surfaces being such as to assurecapillary retention of water in said approach passage; and means forminga water-retaining sump in which the pump housing is mounted, the sumpbeing of depth suflicient to assure submergence of the pump chamber andthe approach passage when the sump is water 4. Thecombination definedinclaim.3in which the impeller rotates on a vertical axis, the housing hasa diameter which is several times its axial extent, and the approachpassage is defined by azplatespacedfrom the upper wall of the housing.

JOHN M. ANDREWS.

BEEEBENCES CITED The following references are of record in the fi Q h s;Pa ent;

UNITED STATES PATENTS

